Sceptics said it couldn't survive the gut. The 2026 RCT in 150 people says it does — and the effect on skin hydration is measurable. Here is what the trial actually showed.
The standard objection to oral hyaluronic acid has always been mechanistic: hyaluronic acid is a large polysaccharide. The gut will degrade it. It will not reach the skin intact. This is a reasonable prior. It is also, based on the accumulating trial evidence, probably wrong — or at least incomplete.
Hyaluronic acid (HA) is not absorbed intact. The sceptics are right about that. What happens instead is that intestinal bacteria and digestive enzymes degrade HA into oligosaccharides — short-chain fragments — which are absorbed through the intestinal epithelium and enter the circulation. These oligosaccharides are not the same as the high-molecular-weight HA found in the dermis, but they appear to act as signalling molecules that stimulate fibroblasts to synthesise new HA in situ.
This mechanism — degradation to bioactive fragments, absorption, and downstream stimulation of endogenous synthesis — is the same general principle that explains why hydrolysed collagen peptides work despite not being absorbed as intact collagen. The gut is not a barrier; it is a processing facility.
The most rigorous trial to date was published in Scientific Reports in 2026 by Dolečková and colleagues. This was a randomised, double-blind, placebo-controlled trial in 150 healthy adults, testing oral sodium hyaluronate at two doses: 60 mg/day (SH60) and 120 mg/day (SH120) for 12 weeks. The HA used had a molecular weight of 1.8 MDa — on the higher end of what is typically used in supplements.
The SH120 group showed statistically significant improvements across multiple skin parameters: enhanced skin hydration and elasticity, reduced transepidermal water loss (TEWL), reduced sebum, and reduced periorbital wrinkle depth. Notably, the trial also measured structural parameters — epidermal thickness and dermal density — using ultrasound, and found significant improvements in both. The SH60 group showed similar but more modest effects.
SH120 significantly enhanced skin hydration and elasticity, reduced TEWL, sebum, and periorbital wrinkle depth, and increased epidermal thickness and dermal density. These are not surface measurements — they reflect structural changes in the skin.
— Dolečková et al., Scientific Reports, 2026
The 2026 trial is the largest and most rigorous, but it is not alone. Kawada et al. (2015, n=60) showed improved skin moisture and reduced wrinkles with 120 mg/day of HA at both 800 kDa and 300 kDa molecular weights. Hsu et al. (2021, n=60) replicated the wrinkle and dry skin findings at 120 mg/day over 12 weeks. A 2025 trial by Nobile et al. (n=88) found that combining oral and topical HA produced additive benefits beyond either route alone.
Vitaei verdict
The sceptical prior was reasonable but the evidence has moved. Oral hyaluronic acid at 120 mg/day has Tier I evidence for skin hydration and structural improvement. The mechanism is indirect but plausible. It is not a substitute for topical HA in acute dryness, but as a daily supplement for skin ageing, the evidence now supports it.
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